The invention refers to devices for the direct conversion of solar energy into electricity, in contrast to indirect conversion involving elevated-temperature intermediary processes producing mechanical torque that is applied to rotary electrical generators. Large solar electricity generators are known to be currently operating in California. All of the largest first concentrate sunlight into high-temperature heat and thereafter, with methods known from combustion-heated power-stations, partially into electricity, the rest waste heat. All currently operating solar power plants with utility-significant electrical-output cover huge tracts because their areal yield is below 3%. Their high cost and considerable height lead to wide east-west separation of concentrator modules. Their high cost is due to the masses of metal required for the wind-loads generated by the height, while the height, ironically enough, is required in order to extend the number of hours per day that each module operates without being shadowed by its southern neighbors. Additional cost factors accrue from the high maintenance labor involved in solar thermal electrical generation.
Large-scale photovoltaic plants have only recently become economically viable due to the steadily decreasing photovoltaic-cell costs and steadily increasing cell efficiency. But without concentration, covering huge tracts of land with banks of one-sun cells will result in large masses of exotic metals being deployed across the landscape, necessarily in large panels that require their own wind-resistant structures. The present invention offers great improvements over this prior art, due to the efficiency-advantages of concentrating sunlight on PV cells.
Theoretically, some photovoltaic cells could convert nearly 50% of the irradiation directly into electricity, and practically nearly 40% has already been achieved in laboratory tests, but both of these are for solar concentration. The prior art of solar concentration, however, leads back to the same excessive land utilization, due to the requirement for modules to be separated. The air-cooled PV concentrators of the prior art are still expensive enough as to require all-day operation for practical payback, because their concentrations are only in the tens.
The prior art suffers from impractically excessive land utilization, which is expressed by their low areal solar efficiency, defined as electricity out divided by sunlight hitting all the land needed by the installation. The present invention offers an environmentally benign system of solar electricity generation that improves upon the aforementioned prior art with a compact, maintainable, resource-modest design that is easy to manufacture and install. By covering 87% of the set-aside land rather than 5%, far less acreage must be set aside per billion watts produced. The present invention offers highly scalable, compact solar-electricity installations with improved logistics of installation, maintenance, and control and improved economics of manufacturing and payback.